When nonfree/nontrivial code is detected in a page, LibreJS attempts to find a relevant contact link or email for the website you are visiting. In order to do so, it will attempt to visit a few links from the current page (for instance, a link labeled “contact” on the same domain as the current page, …)
LibreJS detects contact pages, email addresses that are likely to be owned by the maintainer of the site, Twitter and identi.ca links, and phone numbers.
After LibreJS detects any of the above, a “Complain” tab will appear on the right of your web browser. When you click on this tab, a large panel will appear with contact information. Ideally, at the top you will find the email address of the maintainer, labeled as the “Email you should use”.
Configure the default subject used in complaint emails.
Configure the default body used in complaint emails.